Phase diagram investigations of the Ni–Sn–Bi system

Phase equilibria were studied in the system Ni–Sn–Bi at 733 and 903 K. For this purpose, 30 ternary samples were synthesized using intimately mixed powders. After annealing in quartz ampoules and quenching, all alloys were analysed by scanning electron microscope. Differential thermal analyses (DTA) were done with specimens having chemical compositions near to the expected ternary Bi–Sn eutectic point.Isothermal sections of ternary system at 733 and 903 K were constructed. The phase equilibria between the liquid and the solid phases ((Ni), NiBi, Ni3Sn2 and Ni3Sn4) appeared to be inclined towards the Bi-corner at all temperatures.A formerly unknown ternary compound with approximate formula Ni7Sn2Bi and chemical composition (in mole fractions) XNi = 0.66 ± 0.03, XSn = 0.21 ± 0.02 and XBi = 0.13 ± 0.02 was observed by scanning electron microscopy but it could not be identified by X-ray diffraction analyses.